Wash and soak gram dal and rice together in a bowl for 1/2 an hour.
Cut thick stems portion from Arbi leaves very carefully with the help of sharp knife
First wash leaves with water then dry it with kitchen towel. Keep aside.
Make fine paste of gram dal and rice in chutney jar on medium to high speed. Now add 1 tsp garlic paste, 1 tsp coriander, 1/2 tsp turmeric, 1/4 tsp chilly, 1/2 tsp cumin, 1 tsp amchor powder, 1/2 tsp salt, 2 tablespoon water and mix very well.
First take chopping board then keep largest leaf on the top ; spread thin layer of masala mix all over the leaf. Now put another leaf and repeat same process (thin layer of masala mix). After 4th layer tear leaves in small pieces and spread over it with help of masala mix.
Now we'll make roll of these leaves. First fold outside of leaf then start fold tightly from upper side to down till ends up.
Now tie up with thread. Tie the thread tightly during tie up. It will be helpful while steaming masala mix will not come out and cutting pieces.
While these process are going on keep water for boiling in idly stand/ steamer / momo stand /deep pot or kadai.
Rub little oil on steamer plate / strainer and keep Arbi roll on it. Steam for 15 minutes on low heat so that masala and leaf roll will be cook evenly.
Cool it down for 5 minutes in fan air. Take out thread with the help of knife then cut pieces as mark of thread. Keep aside.
Heat oil in a fry pan /kadai on high flame then reduce on medium heat. Put few pieces in pan and fry it till light brown colour. Keep aside.
Increase heat on high flame. crack panch-phoran for 1 min.or till fenugreek seeds turns pink colour. Now put onion paste and fry for 2 min or onion starts turning light pink colour.
Reduce heat on medium ; add garlic and mustard paste and fry for one min. stir well.
Reduce heat on low flame. now add all dry spices powder except dry mango powder as coriander, cumin, turmeric, black pepper, both chilly powder, tomato pieces, salt,2 tablespoon water in kadai and stir very well. Cover it with lid and fry till oil comes out from masala mixture. it will take 7 -8 min. Stir at least trice while frying.
Now it's time to add dry mango powder and fry one more min.
Add 2 cup of water and give a boil on high flame. Reduce heat drop all fried cutlets in gravy carefully.
Boil it for 10 min.on low flame with half covered lid. Sprinkle coriander leaves and switch off the gas stove.
Serve semi hot colocasia leaves curry with hot steamed rice or hot chapati as per your preference. No dal is required as it tastes like fish curry.